Re: gEDA-user: ngspice transfer function

[cedric <cedric_libre@xxxxxxx>]

Hi r ,

Thanks, that works perfect :-)

Cédric

r wrote :
> Hi,
> 
> There is no DC path from node '1' to the ground (node '0'). Add a
> large resistor between them and the simulation will work:
> 
> Tranfer function
> ISRC 1 0 AC 1
> R1 1 2 1k
> C1 2 3 1u
> R2 3 0 1k
> C2 3 0 1u
> R10 1 0 1e+12
> .AC DEC 10 1 10K
> .END
> 
> Actually, Ngspice tried to fix it by inserting GMIN to the circuit (a
> small conductance between each node and the ground) but for some
> reason it didn't work. Does anyone knows why?
> 
> Cheers,
> -r
> 
> On Sun, Aug 23, 2009 at 10:23 PM, cedric<cedric_libre@xxxxxxx> wrote:
> > Hi,
> > I am a ngspice newbie and I'd like to get a frequential transfer
> > function of a Wien filter
> > as an exercise .
> > I'd like to plot V(3)/ISRC versus frequency .
> >
> > Here is the .sch file I simulate :
> >
> > Tranfer function
> > ISRC 1 0 AC 1
> > R1 1 2 1k
> > C1 2 3 1u
> > R2 3 0 1k
> > C2 3 0 1u
> > .AC DEC 10 1 10K
> > .END
> >
> > Here is the result I get :
> >
> > ngspice 1 -> run
> > Doing analysis at TEMP = 27.000000 and TNOM = 27.000000
> >
> > Warning: Source isrc has no value, DC 0 assumed
> >
> > Warning: singular matrix: check nodes 1 and 1
> >
> > Note: starting dynamic Gmin stepping
> > Trying gmin = 1.0000E-03 Note: One successful Gmin step
> > Trying gmin = 1.0000E-04 Note: One successful Gmin step
> > Trying gmin = 1.0000E-05 Note: One successful Gmin step
> > Trying gmin = 1.0000E-06 Note: One successful Gmin step
> > Trying gmin = 1.0000E-07 Note: One successful Gmin step
> > Trying gmin = 1.0000E-08 Note: One successful Gmin step
> > Trying gmin = 1.0000E-09 Note: One successful Gmin step
> > Trying gmin = 1.0000E-10 Note: One successful Gmin step
> > Trying gmin = 1.0000E-11 Note: One successful Gmin step
> > Trying gmin = 1.0000E-12 Note: One successful Gmin step
> > Trying gmin = 1.0000E-12 Note: One successful Gmin step
> > Warning: singular matrix: check nodes 1 and 1
> >
> > Warning: Dynamic Gmin stepping failed
> > Note: starting source stepping
> > Supplies reduced to 0.0000% Warning: singular matrix: check nodes 1 and
> > 1
> >
> >
> > Trying gmin = 1.0000E-02 Note: One successful Gmin step
> > Trying gmin = 1.0000E-03 Note: One successful Gmin step
> > Trying gmin = 1.0000E-04 Note: One successful Gmin step
> > Trying gmin = 1.0000E-05 Note: One successful Gmin step
> > Trying gmin = 1.0000E-06 Note: One successful Gmin step
> > Trying gmin = 1.0000E-07 Note: One successful Gmin step
> > Trying gmin = 1.0000E-08 Note: One successful Gmin step
> > Trying gmin = 1.0000E-09 Note: One successful Gmin step
> > Trying gmin = 1.0000E-10 Note: One successful Gmin step
> > Trying gmin = 1.0000E-11 Note: One successful Gmin step
> > Trying gmin = 1.0000E-12 Note: One successful Gmin step
> > Note: One successful source step
> > Supplies reduced to 0.1000% Warning: singular matrix: check nodes 1 and
> > 1
> >
> > Supplies reduced to 0.0000% Warning: singular matrix: check nodes 1 and
> > 1
> >
> > Warning: source stepping failed
> >
> > AC operating point failed -
> >
> > Last Node Voltages
> > ------------------
> >
> > Node Last Voltage Previous Iter
> > ---- ------------ -------------
> > 1 0 0
> > 2 0 0
> > 3 0 0
> >
> > doAnalyses: iteration limit reached
> >
> > run simulation(s) aborted
> >
> > Does someone has an idea about what's wrong in the scheme file ?
> > Thanks for your help,
> > ced
> >
> >
> >
> >
> > _______________________________________________
> > geda-user mailing list
> > geda-user@xxxxxxxxxxxxxx
> > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
> >
> 
> 
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